Homes, offices, automobiles, and public spaces are becoming more wired and connected with the proliferation of computing devices such as notebook computers, tablets, entertainment systems, and portable communication devices. As computing devices evolve, the way in which users interact with these devices continues to evolve. For example, people can interact with computing devices through mechanical devices (e.g., keyboards, mice, etc.), electrical devices (e.g., touch screens, touch pads, etc.), and optical devices (e.g., motion detectors, camera, etc.). Another way to interact with computing devices is through audio devices that capture human speech and other sounds using microphones.
Hand gestures may be used by some devices as a way to detect user commands. Hand gestures may be detected by capturing still or video images of the user and analyzing the images to detect trajectories of hands and fingers, and by comparing the detected trajectories with reference trajectories. However, this type of analysis can be difficult to implement within the hardware constraints of many types of devices.